A modified gravity ( MOG ) possesses a light , neutral vector particle called a “ phion ” associated with a vector field \phi ^ { \mu } , which forms a cold fluid of Bose-Einstein condensates before recombination with zero pressure and zero shear viscosity .
The energy density associated with this Bose-Einstein condensate fluid dominates the energy density before recombination and produces a density parameter , \Omega _ { \phi } \sim 0.3 , that together with the fractional baryon density \Omega _ { b } \sim 0.04 , and a cosmological constant parameter \Omega _ { \Lambda } \sim 0.7 yields an approximate fit to the data for the acoustical oscillations in the CMB power spectrum .
The quantum phion condensate fluid is abundant well before recombination and can clump and form the primordial structure for galaxies .
At late times in the expanding universe , in local bound systems such as galaxies ordinary baryonic matter dominates the matter density .
For galactic systems in the present epoch , the modified Newtonian acceleration law determined by MOG describes well galaxy rotation curve data and X-ray cluster mass profile data .